European Journal of Archaeology 24 (3) 2021, 388–411 This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. The Archaeology of a Landslide: Unravelling the Azores Earthquake Disaster of 1522 and its Consequences 1 1 2 CHRISTOPHER GERRARD ,PAOLO FORLIN ,MELANIE FROUDE , 3 1 1 DAVID PETLEY ,ALEJANDRA GUTIÉRREZ ,EDWARD TREASURE , 1 4 KAREN MILEK AND N’ZINGA OLIVEIRA 1Department of Archaeology, University of Durham, UK 2Department of Geography, University of Sheffield, UK 3Research and Innovation, University of Sheffield, UK 4Department of History, Philosophy and Social Sciences, University of the Azores, Portugal The multidisciplinary research described here shows how archaeologists can help reconstruct past seismic episodes and understand the subsequent relief operation, rehabilitation, and reconstruction processes. In October 1522, a major earthquake and landslide struck the then capital of the Azores, Vila Franca do Campo, 1500 km from the European mainland. Damage was extensive, destroying key monuments, affecting most of the inhabited area, and leaving few survivors among the early colonists. The results from twenty-six archaeological trenches, geological and geoarchaeological investigations, and documen- tary analysis are reviewed here. Distinctive archaeological deposits are identified and explained, using the high density of artefacts and the erosional contact between the landslide and the pre-1522 palaeosol to reconstruct the episode in detail. Keywords: Azores, earthquake, landslide, natural hazard, geoarchaeology, archaeo-seismology INTRODUCTION most damaging natural disasters in European history. On 22 October 1522, a powerful earth- Most of what is known about medieval quake (magnitude 5.7–6.7) struck the and early modern tectonic hazards and island of São Miguel in the Azores archi- secondary hazards like landslides has been pelago (Carmo et al., 2013). Intense reported by historians and earth scientists seismic shaking collapsed buildings over a (for an overview, see Guidoboni & wide area and triggered a major landslide Comastri, 2005; Ambraseys, 2009). Only in the hills above Vila Franca do Campo a few field investigations for this period (Figure 1), the earliest and most important have had a specific archaeological focus colonial settlement on the island. An esti- (e.g. earthquakes at Basel in Switzerland mated 3000 to 5000 lives were lost when a in AD 1356: Fäh et al., 2009; Dyrrachium flow of mud and boulders swept through in Albania in AD 1270: Santoro & Hoti, the coastal settlement and out into the sea; 2014; landslides at Onoldswil in the event is still regarded as one of the Switzerland in AD 1295: Akeret et al., © The Author(s), 2021. Published by Cambridge University Press on behalf of European Association of Archaeologists Manuscript received 19 June 2020, doi:10.1017/eaa.2021.4 accepted 28 January 2021, revised 28 October 2020 Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.8, on 30 Sep 2021 at 15:55:29, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/eaa.2021.4 Gerrard et al. ‒ The Archaeology of the Azores Earthquake of 1522 389 Figure 1. Above: location of the Azores (red dot) and São Miguel Island on the triple junction between the North American (NA), Eurasian (Eu) and Nubian (Nu) tectonic plates. Main structures: Mid-Atlantic Ridge (MAR), Gloria Fault (GF), East Azores Fracture Zone (EAFZ) and Terceira Rift (TR). Below: volcanic systems on São Miguel Island with the location of Vila Franca do Campo and other places mentioned in the text. Figure by Melanie Froude and Alejandra Gutiérrez. Map adapted from Madeira et al., 2015 and Trippanera et al., 2014. World topography from NASA, 2018, bathymetry from NOAA, 2018, elevation from ALOS, 2018. 2018; volcanic eruptions and the AD 1343 understanding of impact on the ground Stromboli eruption: Rosi et al., 2019). can be lacking (Ambraseys, 2006: 1009). These projects typically reconstruct events Vila Franca promised precisely dated at a local or landscape scale and assess archaeological deposits from early in the their magnitude or intensity, documenting islands’ documented history, the Azores loss of life and infrastructure, analysing being first claimed for Portugal in AD destruction deposits, and recording evi- 1432, with permanent settlement taking dence for both community preparedness place only after 1449 (Connor et al., 2012; and disaster recovery. Even so, a detailed Rull et al., 2017). In the context of a Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.8, on 30 Sep 2021 at 15:55:29, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/eaa.2021.4 390 European Journal of Archaeology 24 (3) 2021 peripheral maritime community 1500 km 1991) and São Jorge in 1757 (Machado, from the European mainland, the 1970; Farrica, 1980). Secondary hazards responses and adaptions of colonists to have proved especially damaging. At least environmental hazards were also of great a dozen tsunami events have been interest (Gerrard & Petley, 2013; Forlin described over the last 500 years (Cabral, & Gerrard, 2017). Major landslides affect 2009), while on land the risk of landslides dense urban settings every few years is amplified by steep valleys, unstable worldwide. For example, there were an volcano-sedimentary rocks, and a wet estimated 1765 casualties from the August maritime climate (for recent landslides see 2010 Zhouqu landslide in Gansu in Marques, 2004; Marques et al., 2007). China, while the August 2017 landslide in Over the past 5000 years, the island of Freetown, Sierra Leone, killed 1141 São Miguel has experienced thirty erup- people, and two major landslides triggered tions at the Sete Cidades volcano, the by an earthquake claimed 2100 lives in the Fogo volcanic complex, the Furnas town of Beichuan in Sischuan province in volcano and along two basaltic fissure China in 2018 (Yin, 2009). The removal systems (Figure 1). Early colonists of rubble, subsequent relief operations, observed explosive activity and dome and rebuilding activities can impede any growth at Furnas in 1439–1443 (Queiroz understanding of the event and thus any et al., 1995), an event that is confirmed by estimation of future risk. Reconstructing geological evidence (Guest et al., 1999). In what happened, even in modern settings, the centre of Ribeira Grande, the six- is challenging given the low rates of teenth-century ‘Pico de Queimada’ foun- human survival and chaotic nature of the tain was buried under lava flows during an phenomenon. One way forward is to explosive eruption of sub-Plinian (i.e. with examine historic hazard events through volume in the range of 0.05–0.50 km3) archaeological excavation and field obser- scale at Fogo in 1563 (Wallenstein et al., vation. That is the approach adopted here. 2015). There were further eruptions at Furnas in 1630, when some 200 people lost their lives in pyroclastic density flows GEOLOGICAL SETTING (Cole et al., 1995), and in 1652 along the Picos Fissural Volcanic System (Ferreira The Azores lie at the intersection of three et al., 2015). Volcanic sediments provide major tectonic plates: the Eurasian plate ample evidence for hazardous ashfall and on the north side, the African plate to the flows of lava and mud. The presence of south and the North American plate to offshore collapse deposits (Weiß et al., the west, with the Azores Microplate 2016) indicates a major sector collapse of located at the junction (Figure 1). Marked unknown age at Fogo to the south by the Mid-Atlantic Ridge to the north (Sibrant et al., 2015), similar to that on and the Terceira Rift to the south, and the Mount St Helens (Washington, USA) in presence of a volcanic ‘hotspot’ with out- 1982. pourings of basaltic magmas, this dynamic geological setting generates frequent vol- canic eruptions and a high level of seismic HISTORICAL SOURCES AND PREVIOUS hazard (Weiß et al., 2015, 2016). FIELDWORK All nine islands of the Azores have experienced destructive earthquakes (e.g. The Azorean priest and historian Gaspar Terceira in 1614 (Farrica, 1980; Moreira, Frutuoso (c.1522–1591) describes the Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.8, on 30 Sep 2021 at 15:55:29, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/eaa.2021.4 Gerrard et al. ‒ The Archaeology of the Azores Earthquake of 1522 391 1522 earthquake and landslide in his account of the history and geography of the islands, Saudades de Terra (Frutuoso, 1998; see Rodrigues, 1991). This descrip- tion, written fifty years after the event, is complemented by nine seasons of unpub- lished excavations between 1967 and 1981 by Manuel de Sousa d’Oliveira (Bento, 1989). The bulk finds from these cam- paigns, now in the Museum of Vila Franca, were reviewed and catalogued for our project; other materials are on display at the Fundação Doutor Manuel de Sousa d’Oliveira in Ponta Delgada. Unfortunately, Oliveira’s excavation and recording methods do not now permit these artefacts to be linked to the stratigraphy. In addition, an important collection of almost complete pots was recovered in Vila Franca do Campo during the construction of the Centro Municipal de Formação e Animação Cultural in 1991 (Martins, 1996; Sousa, 2011:84).Thesearesaidtobelong to 1522 layers, but stratigraphic details are again absent, and the assemblage also includes later Portuguese tin-glazed wares. Among the finds is an intact rosette window carved in stone (93 cm in diam- Figure 2. Stratigraphic profile from borehole eter), several stone grave markers and two VF45 of the geological context for the 1522 land- copper-alloy candle holders (one intact, 38 slide.